The present invention is related to systems configured for modifying various substrates with multiple modifying agents.
Methods have been developed for the coating or modification of various substrates including textile yarns, fibrous materials, filaments, and the like. For example, polystyrene is known to be a good coating for glass optical fibers to increase durability. These coatings, however, are generally applied in a variety of ways with chemical treatment processes. Some of these methods of chemical treatment (for coating, impregnation, surface modification, etc.) include solvent-based systems and melt-based systems.
Solvent-based chemical treatment systems can include organic or inorganic materials in solutions such as aqueous solutions wherein the organic or inorganic material is dissolved, suspended, or otherwise dispersed in the solution. In the area of coating of glass fibers, U.S. Pat. Nos. 5,055,119, 5,034,276 and 3,473,950 disclose examples of such chemical treatments. Typically, with chemical treatment of some of the prior art, solvents are used to lower the viscosity of the chemical treatment to facilitate wetting of the glass fibers. The solvent is substantially unreactive with the other constituents of the chemical treatment and is driven out of the chemical treatment after the wetting of the glass fibers. In each process for applying solvent-based chemical treatments, an external source such as heat can be used to evaporate or otherwise remove the water or other solvent from the applied chemical treatment, leaving a coating of organic material on the glass fibers. With melt-based chemical treatment systems, thermoplastic-type organic solids can be melted and applied to various fibrous structures. Again, in the area of glass coating, U.S. Pat. Nos. 4,567,102, 4,537,610, 3,783,001 and 3,473,950 disclose examples of such melt-based chemical treatments of glass fibers. These methods and others have been used in the prior art to coat various elongated materials including textile yarns, monofilaments, bundles of monofilaments, and fibrous structures.
Supercritical fluids have been used previously to coat elongated materials such as fibers, metals, and the like. However, when such supercritical fluids have been used, they have typically been applied by one of a few methods. Several of these techniques involve the application of one or more modifying agent by batch soaking in an enclosed chamber. Other methods include processes based upon spraying from a pressurized chamber through a narrow nozzle.
With regard to spray-on deposition, air pressure sprayers have been used to contain supercritical and near-critical fluids (carriers) containing coating material. Upon spraying of the fluid onto the substrate, the supercritical fluid carrier and the coating material leave the high pressure environment and are exposed to a normal atmospheric environment. Thus, the supercritical fluid is exposed to low pressure and evaporates, leaving behind the coating material or modifying agent, which is deposited onto, or modifies the substrate, respectively. Examples of typical spray depositions of the prior art include U.S. Pat. Nos. 4,582,731, 4,734,227, 4,734,451, 4,970,093, 5,032,568, 5,213,851, and 5,997,956. Regarding supercritical fluid batch processes, the substrate is typically immersed and then the pressure is dropped, depositing the coating. This is usually followed by a drying stage. In a related embodiment, fluorocarbon polymers can be used to enhance solubility of polar components in supercritical fluid. However, this is still a batch process.
Though the use of liquified gas, supercritical fluids, and near supercritical liquids and gases have been used to coat solid or other fibrous substrates in the prior art, none presently known by the applicant appear to provide a system for modifying substrates, particularly elongated substrates, with multiple modifying agents in a single continuous system.
The present invention is drawn to a system configured for applying multiple modifying agents to a substrate. The system comprises a first processing chamber configured for applying a first modifying agent to a substrate and a second processing chamber configured for applying a second modifying agent to the same substrate. The modifying agents can be applied in series, one after the other as part of a continuous feed. A first interstitial seal is disposed between the first processing chamber and the second processing chamber. This interstitial seal is optional and can be configured for substantially separating fluids present in each processing chamber. A pair of end seals are also disclosed in relation to the present invention. Specifically, a first end seal can be disposed adjacent to the first processing chamber, and a second end seal can be disposed adjacent to the second processing chamber. Each of the end seals are configured for substantially separating the fluids present in each of the processing chambers from the surrounding atmosphere. A passageway is provided within the device configured for passing the substrate through the first end seal, the first chamber, the interstitial seal, the second chamber, and the second end seal in series.
Though not required, at least one expansion chamber can be disposed between each of the seals and each of the processing chambers. For example, with respect to the first processing chamber, at least one seal can be disposed between the first end seal and the first processing chamber and at least one expansion chamber can be disposed between the first processing chamber and the interstitial seal. With respect to the second processing chamber, at least one expansion chamber can be disposed between the second end seal and the second processing chamber at least one expansion chamber can be disposed between the second processing chamber and the interstitial seal.
Additionally, a method of continuously modifying an elongated substrate with multiple modifying agents can comprise the steps of: a) providing a continuous treatment apparatus comprising a first processing chamber configured for applying a first modifying agent to the substrate, a second processing chamber configured for applying a second modifying agent to the substrate after the first modifying agent is applied to the substrate, wherein each of the first and second modifying agents are substantially isolated from the other; and b) continuously passing the substrate through the first processing chamber and the second processing chamber in series, such that the first modifying agent acts upon the substrate and the second modifying agents subsequently acts upon the substrate.